DE3145022A1 - ELECTRIC UNDERWATER CABLE - Google Patents

Description

MONKS DR. E. WlEGANDt (1932-1980) DR. M. KOHlER DIPl.-ING. C. GERNHARDT

HAMBURG D1PL.-ING. ). GLASSES

DIPL.-ING. W. NIEMANN OF COUNSEL

WIEGAND NIEMANN KÖHLER GERNHARDT GLAESER

PATE NTANWSLTE European patent attorneys

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W. 44 060/81 12 / Ld

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TELEPHONE: 0S9-5 "<M 76/7 TELEGRAMS: KARPATENT TElEXi 529068 KARP D

D-BOOO MDNCHEN2

HERZOG-WILHELM-STR. 16

November 12, 1981

SOCTETA '. CAVI PIRELLI S.p.A. Milan (Italy)

Underwater electrical cable

The invention relates to underwater electrical cables. Into the-. In particular, the invention relates to electrical underwater cables with a hose-like or tube-like Versteifungaexnrichtung are provided where the cables

'.) od in uneven areas of the seabed. Like. Lie.

The present invention also relates to a method for Arranging the hose-like or tube-like stiffening device around the cable, during the Laying process.

It is known that one of the problems which arise with the laying of electrical underwater cables occurs as a result of roughness and irregularities, that are found on the bottom of the water, for example thorn-like or spur-like protrusions, Depressions or depressions, cavities, etc. Such uneven surfaces on the water floor have peaks where the 'Cable remains suspended, as it were', with forces occurring as a result of the 'suspension' which cause the 'endeavor. 'have to bend the cable.

In many cases such forces can be dangerous because they can bend the cable in a radius that is smaller than the minimum permissible bending radius, which means that in such cases damage and not reversible deformations of the cable can be caused ■, whereby these deformations in turn forces occur that tend to bend the cable.

The result is the well-known negative mechanical and electrical consequences, such as deformation or Rejection of the protective cover, mechanical impairment insulation, etc. For example, the minimum permitted bending radius for underwater cables is larger Dimensions, i.e. with an outside diameter of 150 mm,

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about 3 in, and smaller for underwater cables i.e. with an outside diameter of 60 mm, about 1.5 m.

The situation is even more disadvantageous in such underwater zones, in which there are strong currents which will further stress the "suspended" cable will.

In order to eliminate the dangers mentioned, the protective cover could be reinforced and stiffened. Such reinforcement and stiffening is usually obtained in the technique currently used in underwater cables by means of at least one bandage with elongated metal elements.
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However, it has a very rigid armoring that is able to withstand all the stresses that arise Cables that are veril cgi on uneven water, no flexibility that is sufficient to keep the cable on to wind a coil or to wind or to lay it in turns. As a result, the actual laying process cannot are executed.

The reinforcing and stiffening reinforcement mentioned above. is also present over the entire installed cable length, which in many cases represents unnecessary costs, namely in the cases in which, on the water floor, very few uneven Areas to be encountered.

Another solution to the problems mentioned could consist in arranging stationary supports on the water floor which the cable is then arranged. Such a solution can be realized, for example, that flexible Containers are arranged in appropriate places on the water floor. Liquid can then be poured into this container

Cement can be injected or filled in, which then hardens. This technique, which is widely used in the laying of underwater pipes, is in the case of electrical ones
.Cables not applicable well, mainly as a result of the

The fact that the cable is not rigid so that using this technique it is necessary to have a
to provide a very large number of supports, in addition
the supports it would not ensure that the cable
is not possibly shifted under the effect of underwater currents.

Another solution to the above problems could ■ ■ ■,

consist in the fact that the water floor in the area under consideration i

is just done by using the most dangerous j

'Obstacles are removed or destroyed. However, it is

] It is easy to understand that such a solution is neither simple ■

is still economical, especially when surface ■ I

roughness is to be eliminated over a large area

len. . I.

■. ;

■ One purpose of the present invention is "to provide the. J

to overcome the disadvantages mentioned above. Another purpose j

the present. Invention is to use known elec- |

trisehe underwater cables regarding their behavior, '.

2 ^l j if they are "hung up" on bumps in the water bed. [are to improve.

Another purpose of the present invention is. ^

in creating an underwater cable which if there is>

is laid in uneven areas on the water floor, none. · =

is subject to dangerous bends, ie no bending. . \

that are present with a bending radius of; <

smaller than the minimum permissible bending radius for the |

. relevant cable type is. Another purpose is to "■ |

5 ^c j a simple and economical method of production *

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. 1 of such an underwater cable.

An object of the present invention is an electrical one Underwater cable, which has at least one insulated and shielded conductor and a protective cover and which is laid on e.incin Wasner ^ round, which has both smooth and uneven areas. According to the invention, such a cable is characterized that in the areas in which there are uneven areas of the water floor, one around the cable tubular stiffening device is arranged, the rigidity of which is greater than the rigidity of the cable.

A preferred embodiment of the invention is thereby characterized in that the stiffening device is formed from a material, the specific weight of which the specific gravity of water comes close enough.

The invention also includes a "method" /. For arranging a hose or pipe-like stiffening device: i chturif, around an electrical underwater cable. According to the invention, such a method is characterized in that the hose-like or tube-like device is arranged on that cable length during the laying process which is located between the cable winch of the laying vessel and the water. ~

The invention is explained below with reference to the drawing, for example.
30th

Fig. 1 is a schematic view of a length of a. underwater electrical cables ^ according to the invention, which is laid on a water bed and provided with a tubular stiffening device is. .

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l''ifi. ? \ 'M. I'iric the Pig. 1 analogous view of an embodiment in which the tubular stiffening device has a plurality of tubular elements.

Pig. 3 is a schematic longitudinal sectional view of a ' preferred embodiment of a tubular. Stiffening device according to the invention.

Figure 4 is a cross-sectional view of a preferred one Embodiment, wherein an element is shown, which the tubular stiffening device represents.

. ■ Figure 5 is a schematic view · - that provide for the laying of a cable is explained .gemäß the invention.

In Fig. 1, a length of an electrical underwater, kabeis C is shown, which at a depth F on a The water bed is laid, which has an uneven area TA and a smooth or flat area TL.

The cable C, which is at least one insulated and shielded Ladder and a protective cover, which can also be a reinforcement made of elongated metal elements, waiüt, ίat in a zone corresponding to the uneven area TA corresponds to, with a hose or pipe-like stiffening device MT (hereinafter referred to as tubular for the sake of simplicity), at the ends of which a terminal M1 or M2 is located in each case. The two clamping. men Ml and M2 are clamped onto the armouring of the cable C, and they have an outer diameter that is little. at least equal to the outer diameter of the tubular stiffening device MT, such that the tubular

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Vei's stiffener is not along the approach of the cable C can move.

According to the invention, the tubular stiffening "device" has MT has a rigidity greater than the rigidity of the cable C. Under the name "Rigidity" is the ability to understand mechanical deformations to be able to withstand in the presence of stresses, especially in the presence of bending stresses.

The bends that the tubular stiffener MT experiences under stresses, tiind, same Assuming stresses, smaller than the bends that the cable C experiences. In other words, offers a tubular stiffening device according to the invention in the uneven area TA a bending radius that is greater than the minimum permitted bending radius of the cable G. In this way, the ones representing the submarine cable will be Elements, namely conductors, shielding, insulation and protective coating, are not subject to bending, the go beyond the safety limit. Tests have found that the best results are obtained if the specific gravity of the material forming the stiffening device MT is the specific gravity of Comes close enough to water. Therefore plastic 'materials are preferred, for example with glass fibers reinforced polyester, which already has good mechanical properties when glass fibers are embedded in such an amount are that the specific weight of the glass fiber reinforced polyester is about 1.5 kg / dm.

Among the metal materials, only aluminum can be used, which has a specific weight of 2.8 kg / dm, but this specific weight is reduced when the

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Aluminum with substances that protect against corrosion

is treated, for example with bitumen or similar substances, all of which have a specific weight which is less than 1.0 kg / dm.
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The inner diameter of the tubular stiffening device MT is preferably greater than the outer diameter of the cable C. The cable C is held inside the tubular stiffening device MT and coaxially to it by means of special centering elements. Between the outer wall of the cable C and the inner wall of the tubular Vernteifungseinrichtung MT accordingly has an intermediate space which is filled with water flowing in from the outside.
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Water, which can flow in the intermediate space by • passing through special openings, which are formed for example in the terminals Ml and M2, enables a quick and effective consumption or dissipation of heat that is released from the cable during the Use is released. In cases in which the uneven area is comparatively long (see FIG. 2), it is preferred that the tubular stiffening device has a plurality of tubular elements (ETi, ET2., ET3, etc.), denoted by - '"> loin F.eo i gneter connecting elements are connected to one another in series, with, for example, a connecting element Cl connecting the tubular elements ET1 and ET2, a connecting element C2 connecting the tubular elements ET2 and ET3, etc. The connecting means are preferably collars, which connect the opposite ends of the connect adjacent tubular elements to one another or to one another or next to one another.

According to the invention, each tubular element of the tubular stiffening device has a rigidity which is greater

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■ 1 as the rigidity of the cable C. As a result of this condition, the tubular stiffener can have a plurality of tubular members having the same rigidity at its central part and at its end parts. or more tubular elements, which have a rigidity which is less and progressively decreases, from the central part in the direction towards the end part, 'for the purpose of making it the tubular ver. To enable stiffening device "in the zone of transition from a smooth or flat area ^r /, \ x oineiri uneven area to adopt the most suitable shape and accordingly to continuously follow the shape of the cable C, which has a lower rigidity .

Figure 3 is a longitudinal sectional view of a preferred one Embodiment of the tubular stiffening device which consists of a plurality of tubular elements such as ET1, ET2, ET3 and ET4. The tubular Elements ETl to. ET4 are arranged in a row, and the overall structure has a clamp at the beginning and at the end Ml or M2. Each tubular element ET1 to ET ^ possesses a first and a second jacket or corresponding shells 10, 10 ', 11, Tl', 12, 12 'and 13, 13' - .. IHeBe Coats or shells Io to 13 are each C-shaped Cross-section and annular corrugations, i.e. corrugations running parallel to the cutting plane. The coats, which which form the tubular elements are joined together by collars held, with the frets labeled C2, C3 and C4. Each fret has a first and a second half fret 1 * 1, i4 «or 15, 15 'or 16, 16', the C-shaped transverse - ■ have sectional shape and have annular corrugations, i.e. corrugations parallel to the cutting plane. Besides, everyone is Bund with connecting elements not shown in Fig. 3 provided. The geometric properties of the corrugations of each half-fret are similar to the geometric Kipen-

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shafts of the waves of the jackets, and they are such that the wave troughs of the collars are arranged in the wave troughs of the jacket, as can be seen from FIG.
. '

Facing and joining the two half-frets that go around the ends of the two opposite sheath are arranged, with each other -

• leads on the one hand to the fact that the two associated sheaths are connected to one another, so that a tubular element is formed, and on the other hand to the fact that two adjacent sheaths are connected. The collars C3 and C4 ■ have the task, for example, of holding the jackets 10-, 10 '■ and 13 ₅ 13' together around the tubular elements

1'3 ETl and ET4 to form. In contrast, the collar C2 has the function of connecting the jackets 11, 11 'and 12, 12' to one another and also creating a connection with the adjacent jackets 11, 12 and II ¹ , 12 '. In order to make this possible, it is necessary that "the corrugations of the" half-collars 15, 15 '"which form the collar C2" simultaneously engage with the "end corrugations of the jackets 11, 11' and 12, 12 'which the adjacent tubular elements ET2 and ET3 form.

2 ^c j. The two terminals Ml and M2 are similar to the devices that are generally used for fixing electrical cables, for connecting electrical cables, etc. In the case of the present invention, the clamping. men-Ml and M2, however, have an outer diameter which is at least equal to the outer diameter of the tubular elements ET in such a way that they prevent the tubular elements ET from moving along the cable C.

In fact, the inside diameter is any tubular

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Element ET in the area of the wave troughs (in the area of the inwardly protruding parts of the corrugations) greater than the outer diameter of the cable C. Between the outer wall of the cable C and the inner wall of the tubular elements ET is accordingly formed an intermediate space 18 which is filled with water flowing in from the outside.

The cable C is supported in the interior of the tubular elements ET and equiaxed to them by suitable centering elements 19 which, in the case of simpler Aur, ruhrunf ¹ ;: '-shaped projections, can be formed on the inner wall of the tubular elements ET forming jackets 10 to 13 are formed (Fig. 3)

The number of centering elements 19 must be such that the cable G over the entire length of the tubular stiffening device is supported coaxially to this. The centering elements 19 must, however, have openings 19 'which prevents the flow of water in enable room 18.

In the embodiment according to FIG. 3, the water can pass through Openings 17 and 17 'through into the barely 18 that were called are formed in the terminal Ml or in the terminal M2.

·

The use of tubular elements ET, which are provided with corrugations, in particular, but not exclusively being annular corrugations results in certain practical advantages being obtained.

A first advantage is that tubular elements ET are obtained that have good mechanical strength, both against bending forces and against Compressive forces. This property is necessary for cable lengths to be able to support, if the c.an Unobonneitcn of the water bed are "suspended".

Another advantage is that adjacent or successive tubular elements ET connected in an extremely simple and quick manner or can be connected to each other.

The material that the tubular elements ET and the . Forming bundles can be of various types. A preferred material, both for the tubular Elements as well as for the frets is, as already stated above, a polyester reinforced with glass fibers a specific weight of the order of 1.5 kg / dm. The rigidity of the tubular elements can can be changed in accordance with the special requirements by selecting the composition or Mixture of the resin, the thickness of the tubular element and the geometric properties of the corrugations, as well as by using a low weight, whereby the laying

. Operation is facilitated, as explained below. However, there is a condition to be observed, that according to

2Ü of the invention, each tubular element has a rigidity that is greater than the rigidity of the cable.

Another possibility, the rigidity of the tubular stiffening device, which consists of a plurality of tubular elements is composed to "increase", consists in the fact that two or more layers of tubular Elements are arranged one above the other, which means that two or more layers of sheaths are provided. This is preferably carried out in such a way that the coats

'' O each T.ap.e 'with reference to the coats of those below Position in the longitudinal direction of the tubular stiffening. device .staggered and a cutting • 'Present the plane that is to the cutting plane of the mantle of the underlying layer is at right angles.

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In Fig. 4 is a cross-sectional view along line 1-.Γ of Fig. 3 shows an electric underwater cable, which with a pipe arli p, en Versle i f'uiii ^ uyinri cht.imr. is provided. In particular, in-Pip. 4 is a preferred embodiment of the Bund 03 ik; r · Kif ,. 3 shown. The collar has two half-collars 14 and I'M, each of which has a C-shaped cross-section. Each half-collar 14, I ² J 'is at its ends with protruding parts 2O ₅ 20' or 21, 21 ' These protruding parts 20, 21 have through holes through which fastening elements can be passed, for example screws 22 with nuts 22 ', as can be seen from FIG form the means for connecting the half-frets 14, 14 'with a nandor.'

I ¹ M ^. [) is. a schematic i. ". before Dari'.te II uu ( ^r , de :; Wr ¹ 1 e ^ riis of an electrical underwater cable *; which is provided with ci-iier tubular stiffening device according to the invention.

The cable -C is laid to a depth F at which there is a flat area TL and an uneven area TA. Cable C runs when it comes from the deck of the Ship N arranged coil M is withdrawn via the winch V and sinks under the action of gravity below, so that it is relocated to the depth F.

Da: ¹ , cable (J Ί nt mil a pol'ai'l i /■;<.· 11 Veriile.i l'unc ;; u According to the invention, the tubular stiffening device is attached around the cable, to be precise during the laying process

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or on this "arranged between the winch V and the water surface A.

The method for carrying out this operation is particularly easy and quick to carry out if the • tubular stiffening device is of the type as r. ίο is described in do η Figures 3 and k , and in which the following work instructions are observed ":

Iu Kim- ο rod clamp Ml is attached to the protective cover of the Cable C attached.

In contact with the first terminal Ml, a first and a second jacket are arranged around the cable C. which are coupled together to form the tubular element · KTl.

The collar Cl is around the end of the tubular element ETl laid around, which is in contact with the first terminal Ml -'H).

At your {- ^r .t ^v l - '<' HÜhei ·] ying Knde of the tubular element ETL are two more coats around arranged around the cable in such a way "that the tubular member ET2 is formed 2b - '-...

The collar C3 is wrapped around the adjacent ends of the tubular elements ETl and ET2 arranged around.

Using the same procedure, a plurality of 'tubular members ET and collars are thus • arranged that a tubular stiffening device of the desired length is formed.

Kin in I ¹ 'if.-'> not darr.of.t.oü 1 tor covenant is let to the free '>'> Knde "of. '/. Len Rolu-art i gen element of the majority

arranged around by elements.

Finally, a r.wriie terminal M2, not shown in FIG. B, is attached to the protective cover dos Kab.Hr; C fe ;; t, p; e1 e | ^r , l ..

As already said, according to the invention, the pipe-like stiffening device has a rigidity which is greater than is the rigidity of the cable. This means that each of the tubular elements that make up the tubular stiffening device is composed, has a rigidity greater than the rigidity of the cable C. Under this condition, the tubular stiffening device can consist of a plurality of tubular elements ET be composed, all the same. . Have rigidity. Si e · but can only me. eirmr Mehi'r .- 'ih I of tubular elements 1 &quot;. T /,ur.niiimenjjieLU.'L/.L:; a, the have different rigidity.

A practical embodiment that is particularly useful and is effective is that in the central part of the plurality of tubular elements one or more tubular elements of the same rigidity are arranged, while at the end parts one or more tubular elements. Elements are arranged that have less rigidity, the rigidity, starting from the central part, in Direction towards the end parts decreases progressively. In this way, the tubular stiffening device has in the area the end parts are more flexible than the central part. This leads to the fact that the tubular stiffening: /.- device in the zone of transition between uneven areas and smooth or flat areas can adapt very well to the shape of the cable, which, yes, has less rigidity.

The invention was based on electrical

Described underwater cables. It "is to be understood, however, that the invention can also be applied in other areas where similar conditions prevail.

Claims (5)

I β «· • ♦ · »· · O • · · ι .- · · · Claims I. / Electric underwater cable, with at least one insulated and shielded conductor and with a protective coating, the cable being laid on a water bed which has flat and uneven areas, characterized in that a tubular stiffening device (MT) around the cable ( C) is arranged in the zones of the cable which correspond to the uneven areas of the toilet base, and that the tubular stiffening device has a rigidity which is greater than the rigidity of the cable. 2. Cable according to claim 1, characterized in that the tubular stiffening device (MT) - is formed from a material whose specific gravity is sufficiently close to the specific gravity of water. · 3. Cable according to claim 1 or .2, characterized in that the tubular stiffening device (MT) forming material has a specific weight of ^ 2.8 kg / dm (the specific weight of water assumed to be 1.0 kg / dnr). · 4. Cable according to one of claims 1 to 3, characterized in that the material forming the tubular stiffening device (MT) has a specific weight of approximately 1.5 kg / dm. · ■ · ■■ "■. 5. Cable according to one of claims 1 to M, characterized in that the inner diameter of the tubular Stiffening device (MT) larger than the outer diameter of the cable (C), the cable by means of centering elements (e.g. 19, Fig. 3) inside the tubular 3 H 50-22 Stiffening device is arranged coaxially, and that the space (18) between the outer wall of the cable and the inner wall of the tubular stiffening device is filled by the water of the area. 6. Cable according to one of claims 1 to 5, characterized in that the tubular stiffening device "(MT) is arranged in the longitudinal direction between two clamps (Ml ₃ M2) attached to the protective sheath of the cable (C), and that the clamps have an outer diameter which is at least equal to the outer diameter of the tubular stiffener. 7- Cable according to one of Claims 1 to 6, characterized in that the tubular stiffening device consists of one or more tubular elements (ET1, ET2, etc.) arranged in series, and that each of the tubular elements has a rigidity which is greater than the rigidity of the cable is.
■ 8. Cable according to claim ¹ J ₃ characterized in that the tubular stiffening device formed from several tubular elements (ET1, ET2, etc.) in the middle part one or more tubular elements of equal rigidity, and in the end parts has one or more tubular elements which have lower rigidity, and which, moreover, starting at the central one Part, 'progressively decreases in the direction towards the end part in question. _ ■. 9. Cable according to claim 7 or 8, characterized in that on the surface of each tube type Element (ETl, ET2, etc.) annular corrugations are provided. 3U5022 10. Cable according to one of claims 7 to 9, characterized in that each tubular element (KT) is formed by a first and a second jacket (e.g. 10, 10 '), means for connecting the two Jackets and a device for connecting adjacent or adjacent jackets are provided, and that the two sheaths have projections on their inner part which are able to coaxially align the cable (C) to adhere to each of the tubular elements. '. · '11. Cable according to claim 10, characterized in that the facilities for the verb in- . that of the coats (e.g. 10, 10 ') and neberir for connecting of overlapping shells (e.g. 10, 10 'and 11, 11') are frets (C2, C3, C4, etc.). 12. Cable according to claim 11, characterized in that annular corrugations are provided on the surface of the collars (C2, C3j C4, etc.). ■ _. ■ '.. 13 .. Cable according to claim 11 or 12, characterized in that each .Bund a first and has a second half-collar, each of which has a C-shaped cross-section, and that a device (e.g. 20 to 22) is provided in order to connect the half-frets to one another. 14. Cable according to claim 13, characterized in that the means for connecting two half-collars have projections (20, 21) on the two Half-collars and means (22) to connect the projections to one another (Fig. 4). 15. Cable according to one of claims 7 to I ¹ J, characterized in that the tubular 'stiffening device, tubular elements of two or more superimposed layers, · which are arranged in series and composed of sheaths, and that the sheath of each layer in In the longitudinal direction of the tubular stiffening device with respect to the sheaths of the underlying layer are set and present a cutting plane at right angles with respect to the cutting plane of the Mann-Lei in dex ¹ underlying layer. 16. Cable according to one of claims 7 to 15, 'characterized in that the tubular elements and the frets are formed from glass fiber reinforced polyester. 17. A method of arranging a tubular stiffener around an electrical underwater cable, characterized in that the tubular stiffening ; ^J Ü device during the laying process of the cable that part of the length of the cable is assembled, ■ the fi.ich between the one on the pipe-laying vessel Winds and the water surface. 18. The method according to claim 17, characterized in that the following operations are carried out: A first clamp, the outer diameter of which is at least equal to that, is placed on the protective covering of the cable Outside diameter of the tubular stiffening device. is, • Around the cable a first and a second are each- ■ · 3ί> because it has a C-shaped cross-section and annular corrugations 3 H 50 i. j · 1. having sheath arranged around a first tubular * - to form an element which is connected to the first terminal in Touch is located, j 5 around the end of the first tube facing the first clamp I-like element, a collar is arranged, which consists of e i iirm ! . first and a second half-fret ', the C-shaped j. Have cross-section and annular corrugations, the _f 'corrugations similar to the corrugations of the first and the second ! 10 th coat and the inwardly protruding parts' j. of the corrugations of the two half-frets in the corresponding I. outer depressions of the corrugations of the two coats \ are set,. 15 around the cable a third and a fourth man- ; . ' 'tel arranged to have a second tubular element in i. . Row with the or:; th pipe type i-pjon Klomeril, 7, \ x bi] .di; n, . ■ around the facing ends of the first tubular \ ■ 20 element and the second tubular element around ] · 'A covenant is arranged whose inwardly protruding ^ Parts of its corrugations in the outer depressions of the ^: 'End corrugations of the two adjacent or ) adjacent tubular elements arranged \. 25 become, -. I. f I using the procedure described, a ! ■ plurality of tubular elements formed and collars around I ■ the ends of adjacent tubular elements arranged, -. 30 _to a tubular stiffening device with desired i, ■ to form length, ? around the free end of the last tubular element ;; arranged a covenant, and S 35 "* 3H5.022 a * t 1 on the protective cover of the cable. Becomes a second clamp; set whose outer diameter is at least equal to that Outside diameter of the tubular stiffening device ■,! is. ''. '■ 5 '! · ■